Implantable neurostimulator devices are devices that generate and deliver electrical stimuli to body nerves and tissues for the therapy of various biological disorders, such as pacemakers to treat cardiac arrhythmia, defibrillators to treat cardiac fibrillation, cochlear stimulators to treat deafness, retinal stimulators to treat blindness, muscle stimulators to produce coordinated limb movement, spinal cord stimulators to treat chronic pain, cortical and deep brain stimulators to treat motor and psychological disorders, and other neural stimulators to treat urinary incontinence, sleep apnea, shoulder subluxation, etc. The description that follows will generally focus on the use of the invention within a Spinal Cord Stimulation (SCS) system, such as that disclosed in U.S. Pat. No. 6,516,227. However, the present invention may find applicability in any implantable neurostimulator.
As shown in FIGS. 1A and 1B, an SCS system typically includes an implantable pulse generator (IPG) 100, which includes a biocompatible device case 130 formed of a conductive material such as titanium. The case 130 typically holds the circuitry and battery necessary for the IPG 100 to function, although IPGs can also be powered via external RF energy and without a battery. The IPG 100 includes one or more electrode arrays (two such arrays 102 and 104 are shown), each containing several electrodes 106. The electrodes 106 are carried on a flexible body 108, which also houses the individual electrode lead wires 112 and 114 coupled to each electrode. In the illustrated embodiment, there are 16 electrodes on array 102, labeled E1-E16, and 16 electrodes on array 104, labeled E17-E32, although the number of arrays and electrodes is application specific and therefore can vary. The arrays 102 and 104 couple to the IPG 100 using lead connectors 138A and 138B, which are fixed in a non-conductive header material, such as an epoxy.
Prior to the implantation of the IPG 100, external trial stimulators are commonly used to insure that the electrodes 106 are properly placed and to allow configuration of the program of stimulation to be performed by the IPG 100. See, e.g., U.S. Patent Publication No. 2010/0228324 (the “'324 Publication”), discussing external trial stimulators in further detail, which is incorporated herein by reference in its entirety. The external trial stimulator connects to electrode lead wires 112 and 114 external to the body of the patient and provides the ability to stimulate the electrodes 106 similar to the way the IPG 100 stimulates once implanted. Current external trial stimulators however can be difficult to manufacture, or have lacked numerous features that would be useful or more comfortable for the patient, physician, or clinical staff.